Process for the separation of saturated and unsaturated fatty acids or their volatile esters with the simultaneous preparation of condensation products of the unsaturatedfatty acids



United States Patent Ofifice 2,839,551 Patented June 17, 1958 PROCESS FOR THE SEPARATION OF SATURATED AND UNSATURATED FATTY ACIDS OR THEIR 'VOLATILE ESTERS WITH THE SIMULTANEOUS PREPARATION OF CONDENSATION PRODUCTS OF THE UNSATURATED FATTY ACIDS Gerrit Lucas Wiggerink and Everhardus Wilhelmus Jonker, Gouda, Netherlands, assiguors to N. V. Koninklijke Steal-inc Kaarsentahrieken Gouda-Apollo, Gouda, Netherlands, a corporation of the Netherlands N Drawing. Application February 11, 1954 Serial No. 409,762

Claims priority, application Netherlands February 20, 1953 11 Claims. (Cl. 260-419) Various methods for the separation of saturated and unsaturated fatty acids have been proposed.

The best lrnown method is that in which the solidified fattyacids are pressed. This is first effected at room temperature, whcreupon the solid fatty acids obtained, are pressed a secondtime at a higher temperature. .If desired this treatment may be repeated once more.

Furthermore it is known to fractionate fatty acid mixtures by crystallizing them from a solution in an organic solvent and separating the crystalline mass (cf. French Patent 775,700). The crystalline masses obtainedin this way generally are ditlicult to filter unless certain polar solvents are used, and it is desirable to add a substance promoting the crystallization (cf. U. 8. Patent 2,298,501).

Generally speaking these known methods do uot render it possible to obtain in an economical way saturated fatty acids having such a low proportion of unsaturated fatty acids that the iodine number is below about 3.

The present invention relates to a simple, practical and very efficient process for the separation of saturated and unsaturated fatty acids having 8-24 C atoms of esters thereof which is characterized in that a mixture of fatty acids or esters thereof containing .not more than about 10% of unsaturated fatty acids having two or more double bonds and in total not more than about 60%, preferably not more than about 5.0% of unsaturated fatty acids, is heated with an excess of maleic acid anhydride, calcuiated on the unsaturated fatty acids, under such conditions that the unsaturated fatty acids are completely or substantially completely condensed with the maleic anhydride, the unchanged fatty acids or esters being separated from the condensation products by distillation and/ or by treatment with solvents.

The formation of condensation products from unsaturated fatty acids and dienophilic compounds, e. g. maleic acid anhydride, either in the presence or absence of catalysts, is known per se, e. g. from British Patent 500,348 and from U. S. Patents 2,306,281 and 2,444,328. This condensation, however, has never been used for effecting a separation of saturated and unsaturated fatty acids and in general the condensation products have been prepared from mixtures containing so high a proportion of unsaturated fatty acids that they are unsuitable for the recovery of the saturated fatty acids. I Generally speaking the condensation is not complete. in order that the saturated and unsaturated fatty acids be separated to high extent it is necessary :to effect the condensation under such conditions that the unsaturated fatty acids are convert-ed completely or substantially completely into the corresponding condensation products.

To this end it is necessary in the first place to start hydrocarbons, halogenated hydrocarbons and city from a fatty acid mixture containing not more than about 60% of unsaturated fatty acids, while the proportion of unsaturated fatty acids having two or more double bonds should not be more than about 10%.

Furthermore it is necessary to use an excess of maleic acid anhydride calculated on the total amount of unsaturated fatty acids. Preferably a proportion of maleic acid anhydride of at least 200 mol percent is used.

With other dieuophil-ic compounds than maleic acid aniydride a satisfactory separation cannot be achieved.

A very good separation of saturated and unsaturated fatty acids can be obtained if the condensation is carried out in the presence of iodine or compounds capable of generating iodine, as described in copendiug patent application, Serial No. 409,761, filed on even date herewith. The preferred compounds capable of generating; iodine are hydroiodic acid and iodine trichloride. Other compounds which may be used for this purpose are iodine monochloride, iodine monobromide, iodine fluoride, iodoform, hydroiodic acid salts of organic bases, e. g. hexadecylamine or pyridine, and some inorganiciodides, e. g. zinc iodide.

The amount of iodine or of the compounds capable of generating iodine may vary from 0.1% to 2.0%, preferably 054.0%, calculated on the fattyaci ds.

The condensation is carried butqat a temperatureof from to 300 (3., preferably of from K1250 C.

The iodine or the compound capable of generating iodine ca n be added to the mixture of fatty acids and maleic acid anhydride. in that case it is advantageous to effect the addition after the mixture of fatty acids and maleic acid anhydride has, become homogeneous, which is generally the case at temperatures. upwards of 100 C. and preferably after the mixture has been brought to the reaction temperature. However we may also heat the mixture of fatty acids and iodine or. the compound capable of generating iodine to the reaction temperature and thereafter add the maleic acid anhydride.

The time of the reaction depends on the reaction conditions and should be such that all or substantially all of the unsaturated fatty acids are condensed with the maleic acid anhydride. x

If desired the condensation may be carried out in the presence of a high boiling inert solvent, e. hydrocarbons, such as tetraline or deca1ine,.ketones, etc.

After the termination of the condensation the iodine and the excess of maleic acid an-hydride can be removed from the reaction mixture in the manner described .in the aforesaid copending patent application.

As regards the iodine this may be effected, .e. means of activated zinc and water, while the maleic anhydride can be removed by washing with hot water. The iodine may also be distilled from the reaction mixture and subsequently allowed to react with activated zinc. From the zinc iodide formed the iodine may be recovered by means of chlorine.

The mixture of fatty acids and condensation products obtained must now be separated, which can be .eifected by distillation. This separation is based on the fact that the boiling points of the condensation products are com siderably higher than those of the fatty acids, viz. about 60 C. at 1 mm. of mercury, so that a satisfactory separation is obtained by this method.

Separation may also be effected by a .treatment Ni [h a solvent or with mixture of solvents in which the solubility of the unchanged fatty acids and the condensation products is sufiiciently .ditferent. Very suitable for this purpose are aliphatic and cycloaliphatic hydrocarbons, in which the fatty acids readily dissolve, when the addition products are insoluble or hardly solu therein. in most of the other solvents, such as aromatic containing compounds, the addition products will dissolve to too high a degree. A good separation is obtained by means of e. g. petroleum ether, gasoline, cyclohexane and decaline.

' The last mentioned separating method can also be used if instead of the free fatty acids, esters thereof have been subjected to the condensation reaction. The fatty acid esters are also considerably more soluble in the above-mentioned solvents than the condensation products. A separation by distillation is only possible in this case if the starting material consists of volatile fatty acid esters, e. g. methyl or ethyl esters. In the case of non-volatile fatty acid esters, more particularly triglycerides, it is possible, however, to saponify the reaction product or to convert the same into volatile esters by reesterification and subsequently to separate the mixture thus obtained into the condensation products and the fatty acids or the volatile esters by distillation.

The condensation products obtained by one of the above .mentioned separating methods may be used for various purposes, e. g. the production of condensation products with glycols, diamines, etc. If desired they may be purified by redistilling the same in vacuo at elevated temperatures, the non-volatile constituents remaining in the residue. I

' The process according to the invention renders it possible to obtain commercial stearines having an iodine The process is also suitable to produce fatty acids having a very low iodine number, e. g.. below 3, which generally'spe'aking is not possible in an economical way by prior processes. It is true that such fatty acids or fats can be obtained by completely hydrogenating the fatty acids or the oils or fats, but in this case there is no separation between saturated and unsaturated fatty acids and moreover itwill then be necessary to start from very pure fatty acids or fats. According to the invention it iseasily possible to reach an iodine number of e. g. below 1, which is of great importance technically.

' Suitable starting materials for the process according to the invention are e. g. fats originating from the dead corpses of animals, bone fat, yellow grease and brown "grease. From these products stearic acid having an iodine number below 1 can easily be recovered.

As a vegetable starting material we may mention in the first place palm oil fatty acids. Palmitic acid of a high degree of purity can be obtained therefrom; this is an attractive product owing to its particular range of applications. The process may also be used for the removal of unsaturated fatty acids from coconut and palm kernel oil fatty acids.

Furthermore the process can be applied to partly hydrogenated fatty acids and oils provided that after hydrogenation e total proportion of unsaturated fatty acids should be below 60% and the proportion of unsaturated fatty acids having two or more double bonds should be below about 10%.

Finally the process is of importance for the purification of stearine which have been obtained by pressing or by solvent separation and which still have a certain content of unsaturated fatty acids.

The invention, will be elucidated with reference to the following examples.

Example 1 "therefrom by washing with hot water and removing the iodine by means of actvated zinc and water the reaction was dried and the unchanged fatty acids were distilled ed. The iodine number of the distillate was 0.6.

number not substantially exceeding 10 in one treatment.

4 Example 2 grams of palm oil fatty acids (iodine number 44.6) were heated with 40 grams of maleic acid anhydride to 200 C. After 0.5 gram of iodine had been added the mixture was kept at this temperature for 3 /2 hours. After cooling the mixture the excess of maleic acid anhydride and the iodine were removed in the manner indicated above, the fatty acids that had not reacted being distilled oif. The distillate had an iodine number of 5.3.

Example 3 The same experiment was repeated with 60 grains instead of with 40 grams of maleic acid anhydride. The iodine number ofthe distillate now amounted to 0.8.

From the above it appears that when using a larger excess of maleic acid anhydride separation between saturated and unsaturated fatty acids is more complete so that saturated fatty acids having a lower iodine number are obtained.

Example 4 100 grams of fatty acids obtained from a mixture of destruction fat and bone fat, were heated with 66 grams of maleic acid anhydride (300 mol percent, calculated on the unsaturated fatty acids) to 200 C. After the addition of 0.5 gram of iodine the mixture was maintained at this temperature for three hours. After the usual treatment the unchanged fatty acids were distilled off. The iodine number of the distillate was 5.7.

If the time of reaction was 4 hours the same test gave an iodine number of 3.4,for the distilled fatty acids.

' We claim:

1. A process for the separation of mixtures of saturated and unsaturatedfatty materials selected from the group consisting of higher fatty acids and esters thereof into saturated and unsaturated fatty materials, which comprises heating at a temperature within the range of from to 300 C. a mixture consisting of not more than about 10% of fatty material containing at least two double bonds per fatty acid molecule, not more than 60% of unsaturated fatty material in total and at least 40% of saturated fatty material, with an excess of maleic anhydride, calculated on unsaturated fatty material, in the presence of a catalyst selected from the group consisting of iodine, hydroiodic acid, iodine monochloride, iodine tn'chloride, iodine monobromide, iodine fluoride, iodoform, hydroiodic acid salts of organic bases, and zinc iodide, continuing the reaction until the unsaturated fatty materials have substantially completely reacted with the maleic anhydride, and separating the nonreacted fatty material from the adducts formed.

- 2. A process according to claim 1 in which the separation of the unreacted fatty materials and the adducts is effected by distillation.

3. A process according to claim 1 in which the separation of the unreacted fatty materials and the adducts is effected by a treatment with a solvent which dissolves the unreacted fatty material but does not substantially dissolve the adduct.

4. A process according to claim 1 in whichthe proportion of catalyst is 0.1-2.0%, calculated on the fatty material.

hydride at a temperature at which said mixture has become homogeneous.

v 7. A process according to claim 1 in which the catalyst is added to the mixture of fatty material and maleic anhydride after the same has been heated to the reaction References Cited in the file of this patent temperature. UNITED STATES PATENTS S. process according to claim 1 in which the re- 2188 882 Choker Jan 30 1940 iggon camed out at a temperature of between 175 and 5 2,275:843 Clocker Mar. 10, 1942 9. A process according to claim 1 in which the reaction 2537134 Helberger 1951 2,567,404 Ross Sept. 11, 1951 is carried out in a high boiling inert solvent. 2 567 409 T t S t 11 1951 10. A process according to claim 1 in which the mixrem 6P 2,678,934 Grumrmt May 18, 1954 ture of fatty materials is palm oil.

11. A process according to claim 1 in which the mixture 10 OTHER REFERENCES of fatty materials is the mixture of fatty acids obtained Adam et an; Organic Reactions, vol. IV, pages 2 from palm oil. and 3, (copyright 1948). 

1. A PROCESS FOR THE SEPARATION OF MIXTURES OF SATURATED AND UNSATURATED FATTY MATERIALS SELECTED FROM THE GROUP CONSISTING OF HIGHER FATTY ACIDS AND ESTERS THEREOF INTO SATURATED AND UNSATURATED FATTY MATERIALS, WHICH COMPRISES HEATING AT A TEMPERATURE WITHIN THE RANGE OF FROM 120* TO 300*C. A MIXTURE CONSISTING OF NOT MORE THAN ABOUT 10% OF FATTY MATERIAL CONTAINING AT LEAST TWO DOUBLE BONDS PER FATTY ACID MOLECULE, NOT MORE THAN 60% OF UNSATURATED FATTY MATERIAL IN TOTAL AND AT LEAST 40% OF SATURATED FATTY MATERIAL, WITH AN EXCESS OF MALEIC ANHYDRIDE, CALCULATED ON UNSATURATED FATTY MATERIAL, IN THE PRESENCE OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF IODINE, HYDROIODIC ACID, IODINE MONOCHLORIDE, IODINE TRICHLORIDE, IODINE MONOBROMIDE, IODINE FLUORIDE, IODOFORM, HYDROIODIC ACID SALTS OF ORGANIC BASES, AND ZINC IODIDE, CONTINUING THE REACTION UNTIL THE UNSATURATED FATTY MATERIALS HAVE SUBSTANTIALLY COMPLETELY REACTED WITH THE MALEIC ANHYDRIDE, AND SEPARATING THE NONREACTED FATTY MATERIAL FROM THE ADDUCTS FORMED. 